title: Effectiveness of cysteine proteases on protein/pigment film removal.
abstract: OBJECTIVE
  Theaflavin (TF) from the black tea can react to human salivary proline-rich proteins (PRPs) to form stains on exposed dental surfaces. Here, we employed a model of protein/pigment film using TF and dephosphorylated bovine β-casein (Dβ-CN), which has an extended conformation, similar to that of salivary PRPs, on a sensor surface to assess the efficacy of cysteine proteases (CPs) including papain, stem bromelain, and ficin, on removing TF bound to Dβ-CN and the control TF readsorption on the residual substrate surfaces was also measured.
  
  
  METHODS
  The protein/pigment complex film was built by using a quartz crystal microbalance with dissipation (QCM-D). The efficacies of CPs were assessed by Boltzman equation model. The surface details were detected by grazing angle infrared spectroscopy spectra, atomic force microscopy images, and contact angles.
  
  
  RESULTS
  The efficacy order of CPs on hydrolyzing protein/pigment complex film is ficin>papain>bromelain. The results from grazing angle infrared spectroscopy spectra, atomic force microscopy images, and contact angles demonstrated that TF bound on the Dβ-CN was effectively removed by the CPs, and the amount of TF readsorption on both the residual film of the Dβ-CN/TF and the Dβ-CN was markedly decreased after hydrolysis.
  
  
  CONCLUSIONS
  This study indicates the potential application of the CPs for tooth stain removal and suggests that these enzymes are worthy of further investigation for use in oral healthcare.
authors.affiliation: Department of Oral Biology and Biomaterial, Xiamen Stomatological Research Institute, Fujian Medical University, Fujian, China. Electronic address: dentyjw@126.com.
authors.forename: Jiang-Wu
authors.initials: JW
authors.lastname: Yao
authors.forename: Yin
authors.initials: Y
authors.lastname: Xiao
authors.forename: Qi-liang
authors.initials: QL
authors.lastname: Zuo
authors.forename: Yi
authors.initials: Y
authors.lastname: Zhang
authors.forename: Tao
authors.initials: T
authors.lastname: Tao
authors.forename: Chang-Jian
authors.initials: CJ
authors.lastname: Lin
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000494:pharmacology* / Q000627:therapeutic use; D044946:Biflavonoids / Q000737:chemistry* / Q000378:metabolism; D001963:Bromelains / Q000494:pharmacology; D002364:Caseins / Q000737:chemistry; D002392:Catechin / Q000737:chemistry* / Q000378:metabolism; D002417:Cattle; D003546:Cysteine Endopeptidases / Q000494:pharmacology* / Q000627:therapeutic use; D005361:Ficain / Q000494:pharmacology; D006801:Humans; D006868:Hydrolysis; D018625:Microscopy, Atomic Force; D010206:Papain / Q000494:pharmacology; D058525:Quartz Crystal Microbalance Techniques; D055273:Salivary Proline-Rich Proteins / Q000737:chemistry* / Q000378:metabolism; D017550:Spectroscopy, Fourier Transform Infrared; D013499:Surface Properties; D013662:Tea / Q000737:chemistry*; D014075:Tooth Discoloration / Q000188:drug therapy*
chemical_list: D000975:Antioxidants; D044946:Biflavonoids; D002364:Caseins; D055273:Salivary Proline-Rich Proteins; D013662:Tea; C056068:theaflavin; D002392:Catechin; D001963:Bromelains; D003546:Cysteine Endopeptidases; D010206:Papain; D005361:Ficain
keywords: Cysteine proteases; Dephosphorylated β-casein; Film; Hydrolysis; Theaflavin